There are two types of medications which you might be asked to take before anesthesia. The first group is the regular medications or tablets that you are already taking. The second group is additional medications that your doctors might prescribe before your anesthesia and operation or procedure.
You may be taking several different regular medications, particularly if you are older, or have a chronic condition such as high blood pressure, heart disease, asthma, or diabetes. In the past, anesthesiologists often asked their patients to stop taking some of these tablets before anesthesia. However, anesthesiologists now prefer that their patients continue to take almost all their medications, right up to the time of surgery.
There are three major exceptions to this recommendation: some antidepressants, anticoagulants including aspirin, and diabetic medications.
Antidepressants - monoamine oxidase inhibitors or MAOIs
There is a specific class of medications used to treat depression, known as monoamine oxidase inhibitors or MAOIs. There is a probability of a serious medication interaction between the MAOI inhibitor and epinephrine (or adrenaline) or meperidine (Demerol), producing an over-excitation of the brain and a potentially fatal rise in blood pressure. (The same reaction can occur if you are taking an MAOI inhibitor and eat mouldy cheese or drink red wine.) If you are taking this type of medication and you need to have anesthesia, then you and your GP or psychiatrist should arrange for the medication to be stopped before anesthesia. However, if you need to have an emergency operation or have not stopped taking the medication, tell your anesthesiologist so he or she can avoid giving you any of the medications which may interact.
Anticoagulants and aspirin
These medications are used to thin the blood. If you are taking warfarin or coumadin, then you must check with both your anesthesiologist and surgeon for specific instructions on when and how to taper the dose of these medications. If you have had a stroke or been threatened with one, you may be taking a type of medication known as an anti-platelet agent, or one of the non-steroidal anti-inflammatory medications such as aspirin. You may also be taking aspirin because of heart problems or arthritis. Again, you should check with your anesthesiologist and surgeon. These medications have an effect on how certain cells in the blood stream (platelets) stick to each other when blood clots. Because the cells are no longer so sticky, there can be more bleeding during and after operations. The effects of these medications on blood clotting may last for as long as 14 days. Some patients can stop taking these medications without any problems before anesthesia and surgery. However, other patients should not stop them, including those with very bad heart disease or a past stroke. Also, patients who rely on these medications for relief of pain and other symptoms from their arthritis may find that their joints are much more painful if they stop the tablets. Again, it is vital that you ask the doctor who normally looks after you, as well as your anesthesiologist and surgeon.
Diabetic medications and insulin
If you normally take tablets for the control of blood sugar for diabetes, you should not do so on the day you are to have anesthesia. If you do so and then go without eating (fasting), your blood sugar might drop very low while you are under anesthesia, when you cannot complain of the symptoms of low blood sugar or hypoglycemia. In addition, one of these medications, metformin, has been associated with the development of a severe condition where acid builds up in the blood stream. The probability of this developing is more likely in patients who undergo certain procedures, such as heart operations where the heart-lung machine is used.
On the other hand, if you are taking insulin for control of diabetes, you will want to discuss how best to manage your insulin. Ideally, patients with diabetes should be scheduled to undergo their procedures as the first case of the day. This will allow them more time during the day to recover and perhaps be able to start back on a reasonably normal diet. Some diabetics will be asked to take less than their normal dose of insulin. A few diabetics might even omit taking any insulin until the procedure is over and they are capable of eating or drinking again. All diabetic patients should have their blood sugar tested immediately before the operation and again when they arrive in the recovery room. Some patients also have their blood sugar tested during the procedure by their anesthesiologist.